I first met Kathryn in 1994 as a member of the BBC Design Awards jury. We were sent to film Ushida Findlay’s intriguing truss wall house in Tokyo, and to interview her and her partner Eisaku. The house was extraordinary – technically, spatially and sculpturally – and astonishingly built without the sophisticated software that has since become the norm. We also got a tour of the firm’s completing ‘Soft and Hairy House’ – a domestic scale ziggurat that pulled the bushy landscape up a ramped roof enclosing a courtyard into which projected the most exotic coloured sculptural volumes.

In these two houses alone one could sense the sheer inventive joy that pervaded everything Kathryn touched, and how versatile and site/client specific these two ­entirely different projects were. What also came across strongly in that first meeting was Kathryn’s generosity and humour, and her natural humility. She was desperately keen that Eisaku should have at least as much time as she in front of the camera even though it was clear that she was a born communicator while Eisaku was a man of many ideas but few words. So a hilarious ritual developed where Eisaku was placed before the camera and asked a question; after a few seconds, he would turn and exclaim ‘Kathryn’, who then stepped up and performed.

She could be mischievous as well as brilliant. Dew­hurst Macfarlane teamed up as engineer with Ushida Findlay for the Millennium Thames Bridge competition and we found ourselves in the last five. Her entry was the only one to break the rules – it was distinctly her idea to line up the bridge with the passage through to St Pauls, rightly recognising that the vista when crossing the bridge was more important than the intermittent view from a river boat – but although she didn’t win the competition the victorious scheme did adopt this strategy.

Living in Japan as a foreign woman in a male dominated profession is by all accounts not easy. But Kathryn excelled in this close knit society, becoming a rare – if not the only – female foreign professor in the architectural department of the University of Tokyo and one of the most interesting architects to have practised in Japan. In 1995 I met Kathryn in her Tokyo office. This was the tiniest space, packed with a most extraordinary array of models, drawings and collected objects, and into it she also managed to shoehorn two or three staff, Eisaku and herself. You could sense here the range of forms, colours and textures that reflected the richness of her imagination and the extraordinary constraints under which they produced such exceptional work. Their home, true to the Japanese norm, was as tiny as their office.

It was perhaps this compressed constraining condition that finally led Kathryn to return to London. When she and her son Hugo arrived, they came to visit us in our still bare new apartment. Although not large by London standards the space was liberating for Hugo who ran from one side of the flat to the other again and again. Once back in London Kathryn quickly established an office and, relishing her new freedom, was in no time working on exceptional schemes for clients in Doha. Unfortunately her natural trust in her clients was not reciprocated; fees were not paid in time and she had to dissolve the practice.

Resourceful as ever and undaunted, she took a teaching position at Dundee University and set up a university-based studio, later re-establishing her London office. She was quickly back in the limelight with the design of a contemporary country mansion, Grafton New Hall – otherwise known as the ‘starfish house’ – which set a precedent by winning planning consent for a new house on a green field site that later became a model for changes to planning policy. The downturn prevented the project’s realisation but she kept busy as architect on the Arcelor­Mittal Orbit for the 2012 Olympic Games, collaborating with artist Anish Kapoor and engineer Cecil Balmond.

We have lost a wealth of possibilities with Kathryn, and for many of us who had the privilege of knowing her personally, we have lost a loyal and true friend.